Due to the relatively brittle and crushable nature of gypsum board and joint compound applied to conceal the joints between adjacent gypsum board panels, a metal corner bead is typically applied to cover corners where adjacent gypsum board panels meet. The metal corner bead typically consists of a long, narrow strip of sheet metal folded widthwise along its center line so as to provide a V-shaped cross-section across its width with the portions of the strip opposite the center line being adapted to be secured to the two adjacent boards where they join at a corner. When viewed in cross section, the strip portions typically extend perpendicular from the center line to one another. However, the angle formed in the strip may be at other angles when the panels forming the corner to be covered with a bead are not perpendicular to one another. In some instances the two strip portions of a corner bead meet at a rounded "nose" so that rounded corners between panels can be provided. Traditionally, these rounded corners have been formed with a relatively small (about 0.01") radius, although recently corner beads with relatively larger radii (about 0.5-1.5") have been formed. The large-radius beads are typically referred to as bullnose corner beads. Often, corner beads include perforated paper attached to the inner and outer surfaces thereof.
One method of finishing the corners of adjacent panels involves installing a corner bead so as to cover the portions of the panels meeting at a corner. This installation is accomplished by inserting sheet rock screws or other fasteners through apertures in the beads and into the panels. Then, multiple coatings of joint compound are applied to the beads and sanded until a smooth corner is achieved.
Another technique for attaching corner beads involves applying joint compound to the inner and outer surfaces of a bead, and then pressing the bead against the corner. As the joint compound on the surfaces of the bead dries, an adhesive bond is achieved between the wall and the corner bead. As such, the need to attach the bead to the corner with fasteners is avoided. After the joint compound on the bead has dried and has been sanded, additional layers of joint compound are typically applied and finished.
Although the above-described processes for finishing a corner where adjacent panels meet produce a satisfactory corner, these processes tend to be relatively labor intensive, and hence costly. In particular, it takes a significant amount of time to apply and sand the joint compound so as to achieve a smooth corner. Additionally, when a corner bead is applied without the use of fasteners, it tends to be difficult to apply an even thickness of joint compound to both surfaces of the corner bead.